A thermal compression bonding process is a process used to assemble/package a flip chip, die or semiconductor device to a packaging substrate. Such a flip chip is often referred to as a thermal compression flip chip (TCFC). FIG. 1 illustrates an example of a package that includes a chip/die coupled to a substrate using a thermal compression bonding process. As shown in FIG. 1, a package 100 includes a die/chip 102 that is coupled to a substrate 104. There are several electrical connections 106 and a non-conducting paste (NCP) 108 between the chip 102 and the substrate 104. The electrical connections may be defined by under bump metallization (UBM) structures (e.g., UBM structure 110), solder (e.g., solder 112) and traces (e.g., trace 114). The NCP 108 provides a protective layer that covers the electrical connections between the chip 102 and the substrate 104.
FIG. 2 illustrates an example of how a chip/die may be assembled to a package by using a thermal compression bonding process. Specifically, FIG. 2 illustrates a package 200 and a die 202. The package 200 includes a packaging substrate 204 and several traces 206a-c. FIG. 2 also illustrates a non conductive paste (NCP) 208, which is usually dispensed on top of the traces 206a-c before thermo-compression is done. The NCP 208 may have fluxing capabilities, which means the NCP 208 may be capable of removing oxide from materials (e.g., remove oxide from humps and/or traces). Oxide is a material layer that may be formed on the surface of an underlying material when the underlying material is exposed to air, water and/or other chemicals. The die 202 includes several bumps 210a-c. Each of the bumps 210a-c respectively includes copper pillars 212a-c and may also include solders 214a-c. 
One of the challenges with a thermal compression bonding process is controlling or preventing the oxidation of the trace, which can lead to weak joints or non-connects. A trace is typically made of copper, which can be easily oxidized. That is, an oxide layer easily forms on the copper surface. As mentioned above, oxidation occurs when the material is subject to air, water and/or other oxidizing environments. Oxidation may be problematic because oxide on a material may prevent solder from properly wetting to the material. Thus, one of the problems that may arise during a thermal compression bonding process is that the solder (e.g., solder 214b) may not properly wet with a trace (e.g., trace 206b) on the substrate side, therefore preventing a good joint from forming between the solder and the trace. Thus, in some implementations, the result of the oxide on the trace is an open or poor joint. In an open joint, there is no connection between the solder and the trace. In a poor joint, the connection between the solder and the trace is very weak and will likely fail over the life of the die and/or package.
FIG. 3 illustrates a die assembled to a package after a thermal compression bonding process. Specifically, FIG. 3 illustrates the package 200 and the die 202 of FIG. 2 after a thermal compression bonding process. As shown in FIG. 3, the bump 210a is coupled to the trace 206a. Similarly, the bump 210b is coupled to the trace 206b, and the bump 210c is coupled to the trace 206c. As shown in FIG. 3, the joint between the solder 214b (of the bump 210b) and the trace 206b is poor, as illustrated by the fact that the solder 214b is barely in contact with the trace 206b. Although there is a connection between the solder 214b and the trace 206b, this connection will eventually fail. In contrast, the joint between the solder 214a and the trace 206a is better, since the solder 214a is in contact with more surface area of the trace 206a. 
Therefore, there is a need for an improved design to ensure solid joints are created between solder and trace.